-LRB- CNN -RRB- -- Joe McGinniss could not believe his eyes . The man he saw in a North Carolina courtroom last week was stooped and shackled , hardly the same smooth and swaggering Jeffrey MacDonald who had told his story so many years ago .

To say the author and the convicted killer have a history would be an understatement . If anything , their first face-to-face meeting in 35 years was anticlimactic .

`` He looked like a shadow , '' McGinniss said of MacDonald , now 68 , who some believe the author betrayed for his 1983 best-selling book `` Fatal Vision . ''

`` He has a pallor , there was no substance to him , '' McGinniss continued . `` I guess many years in prison can do that to you . ''

McGinniss testified earlier this month for the prosecution at a federal hearing in Wilmington , North Carolina , that could determine whether or not MacDonald deserves freedom , or at least a new trial .

MacDonald 's lawyers assert that newly-discovered DNA evidence -- three hairs that match neither MacDonald nor any of the victims -- and the secondhand confession of a key witness who claimed to be at the family 's home the night of the murders justify reopening the case .

Judge hears new evidence in ` Fatal Vision ' case

McGinniss said in court that he considers the latest defense maneuver to be `` the Holy Grail , '' MacDonald 's last chance at freedom . He remains convinced of MacDonald 's guilt .

The attorneys finished their closing arguments on Monday , and the decision is now in the hands of U.S. District Judge John C. Fox . The judge could let MacDonald 's murder convictions stand , toss them out , or order another trial . It is expected to take weeks , perhaps months , before a ruling comes in a criminal saga that has made headlines for four decades .

It began when military police officers were summoned to the MacDonald home at Fort Bragg , North Carolina on February 17 , 1970 . Inside , they found a horrific crime scene . MacDonald 's pregnant wife , Colette , was stabbed 16 times with a knife and 21 times with an ice pick . Daughter Kimberly , 5 , was bludgeoned and stabbed in the neck . Kristen , 2 , was stabbed 48 times ; a finger was nearly severed as she tried to fend off the blows .

`` It was overkill , '' said McGinniss , who wrote that MacDonald killed his family in an amphetamine-fueled rage .

MacDonald , a captain assigned to the Green Berets , also sustained a collapsed lung and two stab wounds in what he said was an attack on his family by a trio of intruders , including a woman in a floppy hat who chanted `` Acid is groovy '' and `` Kill the pigs . '' The word `` pig '' was written in blood on a headboard , a detail reminiscent of the infamous 1969 Manson family murders in California .

Prosecutors alleged MacDonald staged the crime scene .

The Army investigated first , and MacDonald was cleared at a closed military hearing . But his father-in-law pushed civilian authorities to pursue the case and a grand jury indicted MacDonald in 1975 . He was found guilty of murder four years later and is serving a three life sentences . If his appeal fails , he does not become eligible for parole until 2071 .

MacDonald has always insisted he is innocent , so the recent developments in the case come as no surprise to McGinniss .

`` He 's a psychopath . He does n't have the kind of emotions that you and I would have , '' the author said . `` He does n't have the capacity to feel badly about it . These were n't his wife and children . These were people that got in his way . ''

MacDonald 's appeals received renewed attention with the release this month of the book `` A Wilderness of Error : The Trials of Jeffrey MacDonald . '' Written by Academy-Award-winning documentary filmmaker Errol Morris , the book paints MacDonald as a man wrongly convicted on the basis of incomplete and corrupted evidence , as well as prosecutorial misconduct .

`` We 've been sold a bill of goods about this case , '' said Morris . `` It 's as phony as a three-dollar bill . ''

Writer seeks to clear MacDonald

Asked about the controversy , McGinniss was pragmatic in his response .

`` It does n't matter what I think of what Morris thinks , '' he said . `` MacDonald was convicted by a jury in a court of law . He 's not in prison because of me and he 's not going to get out of prison because of Errol Morris . ''

McGinniss also tried to put the rest the notion that he was a passionate believer in MacDonald when he embarked on `` Fatal Vision . '' He says he was embedded with the defense team because he was looking for a different angle .

`` I thought it would be fascinating to write about the trial from the point of view of how the defense and defendant were experiencing it . I learned everything from the first time in court . I did n't have my mind made up . ''

McGinniss said what he heard in court was overwhelmingly convincing .

`` There came a point in the trial when much to my dismay I started to feel this evidence is piling up and MacDonald is n't doing anything to dispute it . By the end it was still very confusing . I said to myself , ' I think this guy did it , ' but he was so charismatic and likable and had such a strong personality . This was before I learned about the psychopathic personality . ''

McGinniss also disputed the notion raised by the defense and Morris that the prosecutor at the criminal trial threatened witness Helena Stoeckley to alter her testimony . Stoeckley , who died in 1983 , had admitted to others that she was present for the killings but she denied it on the witness stand at MacDonald 's trial .

Watching MacDonald in court again reminded McGinniss of how much has changed in the three decades since he last laid eyes on him .

`` It was in 1987 during the trial of the civil suit against me , '' McGinniss said . `` He was allowed to wear a new suit of clothes . He looked like the host of a daytime game show . ''

In the civil case , MacDonald accused the author of breaching an agreement to write a book about his innocence . The jury deadlocked and the case was settled out of court for a reported $ 325,000 . Journalist Janet Malcolm wrote a widely read article about the case and was critical of McGinniss , accusing him of deceiving MacDonald by pretending to believe he was innocent after becoming convinced of his guilt .

McGinniss now has another controversial book out , `` The Rogue , '' a biography of Sarah Palin .

In court , MacDonald literally seemed to McGinniss to be a ghost from the past .

`` The years since have not treated him kindly , '' he said . `` He sat there at the end of the table and was whispering . He seemed insubstantial .

`` I looked at him but he would never look me in the eyes . ''

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Author Joe McGinniss wrote about Jeffrey MacDonald in ` Fatal Vision '

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Former Green Beret doctor was convicted in 1979 of killing pregnant wife , daughters

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MacDonald maintains his innocence , accuses author of betraying him

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McGinniss was a witness against MacDonald at recent court appeal